ML20101F487

Proposed Tech Spec Sections 3.8 & 5.6 Re Insertion & Withdrawal of Spent Fuel Shipping Cask in Pool 1,eliminating Restriction of Assemblies Stored Onsite

ML20101F487
Person / Time
Site:	Prairie Island
Issue date:	12/21/1984
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20101F457	List: ML20101F455 ML20101F469 ML20101F487 ML20101F501
References
TAC-56614, TAC-56615, NUDOCS 8412270189
Download: ML20101F487 (8)

Text

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c. TS.3.8-1 REV R

3.8 1 REFUELING AND~ FUEL HANDLING

' Applicability Applies to operating' limitations during fuel-handling and refueling operations.

- Obj ectives -

To ensure that no incident could occur during fuel handling and refueling operations that would affect public health and safety. .

e Specification

! .A. During . refueling operations the' following conditions shall be satisfied:

1. . The equipment hatch and at least one door in each personnel air lock shall be closed. In addition, at 'least one isolation valve shall be operable or locked: closed in each line which . penetrates the contain-

- ment and provides a direct path from containment atmosphere -to the

-outside.

2.' . Radiation levels in fuel handling areas, the containment and the spent:

fuel storage pool areas shall be monitored continuously.

3. The core suberitical neutron flux shall be continuously monitored by at least two neutron monitors, each with continuous visual indication in the control room and one with audible indication in the containment, which are in service whenever core geometry is being changed. When core geometry is .not being changed, at least one neutron flux monitor shall be in service.

4.. During' reactor vesse1 head removal and while loading and unloading fue1 from the reactor, the minimum boron concentration of 2000 ppm shall' be maintained in the reactor coolant system. The required boron concentra--

tion shall be verified by chemical analysis daily.

5. . During movement of fuel assemblies or control rods out of the reactor vessel, at least 23 feet of water shall be maintained above the reactor vessel flange. The required unter level shall be verified prior to

. moving fuel assemblies or control rods and at least once every day while the cavity is flooded.

. 6. At least 'one residual heat removal pump shall be operable and running.

The pump may be shutdown for up to one hour to facilitate movement of fuel or core components.

7. If the unter level above the top of the reactor vessel flange is less -

than _20 feet, except for control rod latching and unlatching operations, both residual heat removal loops shall be operable.

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8. -If Specification 3.8.A.6 or 3.8.A.7 cannot be satisfied, all fuel handling operations in containment .shall be suspended, the containment, integrity requirements of Specification 3.8.A.1 shall be satisfied, and no reduction in reactor coolant boron concentration shall be made.

9. Direct communication between the control room and the operating floor of - the containment shall be available whenever changes in core geometry are taking place.

10. No movement of -irradiated fuel in the reactor shall be made until the reactor ~has been suberitical for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />.

11. The radiation monitors which initiate isolation of the Containment Purge System shall be tested and verified to be operable immediately prior to a refueling operation.

B. ruring fuel handling operations, the following conditions shall be satisfied:

1. Prior to introducing a spent fuel shipping cask into the spent fuel pool area:

a. A minimum boron = concentration of 1800 ppm _shall be maintained in -

spent fuel pools No. I and 2. The required boron concentration shall be verified by chemical analysis daily while use of the cask continues, and

b. A cask impact limiter determined to be capable of absorbing the impact energy of a cask drop or a crash pad capable of absorbing the impact energy of a cask drop shall be in place, and

c. Crane interlocks and mechanical stops limiting travel to the approved

. load path shall be determined to be operable, and

d. Fuel-in the small pool (pool No.1) shall be discharged from a .

reactor for at least 50 days.

2. Prior to spent fuel handling in the auxiliary building, tests shall be made to determine the operability of the spent fuel pool special ventilation system including the radiation monitors in the normal ventilation system that actuate the special system and isolate the normal systems.

3. Prior to fuel handling operations, fuel-handling cranes shall be load-tested for operability of limit switches, interlocks, and alarms.

4. When the spent fuel cask contains one or more fuel assemblies, it will not be suspended more than 30 feet above any surface unless the fuel has decayed more than 90 days.

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5. No more than 45 recently discharged assemblies shall be located in the  !

small pool (pool No.1) .

C. If any of the specified conditions in 3.8.A or 3.8.B above are not met, refueling or fuel-handling operations shall cease. Work shall be i initiated - to correct the violated conditions so that the specifications are met, and no operations which may increase the reactivity of the core shall be performed. '

-D. . Spent Fuel Pool Special Ventilation System

1. Except as specified in . Specification 3.8.D.3 below, both trains of the Spent' Fuel Fool Special. Ventilation System and the diesel generators

, required for their operation shall be operable at all times.

2. a. The results of in-place DOP and halogenated hydrocarbon tests at

design flows on HERA filters and charcoal adsorber banks respectively shall show ji99% DOP removal for particles having a mean diameter of 0.7 microns and ji99% halogenated hydrocarbon removal.

.b. The results of . laboratory carbon sample analysis shall show ji90%

radioactive methyl iodide removal efficiency (130*C, 95% RH).

c. The Spent Fuel Pool Special Ventilation System fans.shall operate within 210% of 5200 cfm per train.

3. From and af ter the date that one train of the Spent Fuel Fool Special Ventilation System is made or found inoperable for any reason, fuel handling operations are permissible only during the succeeding seven days (unless such train is made operable) provided that the redundant train is verified to be operable daily.

i 4. ~ If the conditions for operability of the Spent Fuel Pool Special Ventilation System cannot be met, fuel handling operations in the Auxiliary Building shall be terminated immediately.

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TS.3.8-4 REV Basis

.The equipment and general' procedures to' be utilized during refueling are dis-cussed in the FSAR. Detailed instructions, the precautions specified above,

- and theidesign of . the fuel handling . equipment incorporating built-in inter- -

locks and safety ' features, provide assurance that no incident could occur.-

during the andsafety.(({uelingoperations.thatwouldresultinahazardto-publichealth Whenever changes are not being made in core geometry,~ one flux

' monitor is sufficient. This permits maintenance of:the instrumentation. Con-tinuous monitoring of radiation levels and' neutron flux provides immediate indication of an unsafe condition. The residual heat removal pump is used to

. maintain a~ uniform boron concentration.

lThe' ehutdown margin indicated in A.4. above will keep the core subcritical, even if's11 control rods were withdrawn-from the core. During refueling, the

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. reactor refueling cavity is filled with approximately 275,000 gallons of borated

-water. The boron concentration of this water is sufficient to maintain the-reactor suberitical by approximately 10% Ak/k in the cold condition with all

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rods inserted, and will also maintai rodswereinsertedintothereactor.T2fhecoresubcriticalevenifno. control 1 Periodic checks of refueling water boron concentration. insure that proper shutdown margin 'is. maintained. _ A.9.

above allows the control room operator to inform the manipulator operator of-any impending unsafe condition detected from the _ main ' control board indicators

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during fuel movement.

No movement of fuel.in the reactor is permitted until the reactor has been suberitical for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> to permit _ decay of the fission products in the fuel.

analysis.(3Jhe delay time is consistent with the fuel handling accident The -spent fuel assemblies will be loaded into the spent fuel cask af ter sufficient decay of fission products. While inserting and withdrawing the cask into pool No.1, the cask will be suspended above the bottom of the pool up to a maximum of 42 feet. The conseqQances evaluatedinaccordancewithNUREG-0612(69.tential1addropshavebeen Following is a discussion of the basis for the limitations which resulted from that evaluation.

I The cask will not be' inserted into the pool until all ' fuel stored in the pool has been discharged from the reactor a minimum of 50 days. The 50 days will

. allow sufficient decay of the fission products such that their release would result in of fsite doses less than 25% of the 10CFR Part 100 guidelines. The

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[ cask wil1~ not be inserted or withdrawn from the pool unless a minimum boron concentration of 1800 ppe is present. The 1800 ppa will ensure that if fuel

'is crushed by a cask drop, k will be less than or equal to 0.95. The cask 3 will not be inserted or withI hwn from the pool unless a cask impact limiter, crash pad, or combination thereof is in place with the capability to absorb 4

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' energy of L a cask drop such that no sigificant amount of water leakage results

, Ofrom pool. structural damage. This is to ensure that at no. time will water U level' drop below sthe ' top of the spent -fuel stored infeet.gyl. the g In loading the caskintoa. carrier,thereilsapotential'dropof66

. The cask will not 'be loaded onto the carrier for shipment prior to a 3-month storage period.

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, At this' time, the radioactivity.has decayed so that a release of fission products .from all fuel' assemblies in the cask would result in off-site doses

1ess than 10 CFR.Part.100. It is assumed, for this dose analysis that 12 assemblies rupture after storage for 90 days. Other assumptions are the same i as ;those used in the dropped fuel assembly accident in _the SER, Section 15. The resultant doses at the site boundary are 94 Rams to the thyroid and 1 Rem whole j'

2 body.

- The Spent Fuel Pool Special Ventilation System ('} is'a safeguards system which

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, ft maintains a negative pressure. in the spent fuel enclosure upon detection of high area radiation. The Spent Fuel. Pool Normal Ventilation system is auto-matically isolated and exhaust air is drawn through filter modules containing '

a roughing filter, particulata filter, and a charcoal filter before discharge to 1 the environment via one of the Shield Building-exhaust stacks. Two completely 7 redundant trains are provided. The exhaust fan and filter of each train are shared with the1 corresponding. train of the Containment In-service Purge System.

High efficiency particulate absolute (HEPA) filters are installed before the charcoal-adsorbers to prevent clogging of the. iodine adsorbers in each_SFPSVS

' filter train. The charcoal adsorbers are installed to reduce the potential

- release of radioiodine to the environment. The in-place test results should

. indicate a HEPA filter leakage of less than 1% through DOP testing and a charcoal P

adsorber leakage of less than 1% through halogenated hydrocarbon testing.= The

• i . laboratory carbon sample test results should indicate a radioactive methyl iodide t '

removal efficiency of st least 90% under test conditions which are' more severe

than' accident conditions. 1 Nun satisfactory completion of these periodic tests combined.with the qualification. testing conducted on new. filters and adsorber 4

provide a high level of assurance that the emergency air treatment systems will perform as predicted in the accident analyses.

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During movement of irradiated fuel assemblies or control rods, a water level of 23 feet is maintained to provide sufficient shielding.

The water level may be lowered to the top of the RCCA drive shaf ts for latching

- and unlatching. - The basis for this allowance is (1) the refueling cavity pool '

has sufficient level to allow time to initiate repairs or emergency procedures t

to cool the core, (2) during latching and unlatching the level is closely i monitored because the activity uses this level as a reference point, (3) the

. time spent at this level is minimal, j p <

References (1) FSAR Section 9.5.2 (2) FSAR Table 3.2.1-1 (3) FSAR Section 14.2.1  ;

(4) FSAR Section 9.6  :

(5) FSAR Page 9.5-20s

'(6) Exhibit C, NSP License Amendment Request Dated December 21, 1984.

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REV S.6 FUEL HANDLING l l

' A .' ' Criticality Consideration The new and spent fuci pit structures are designed to withstand the J . anticipated earthquaka loadings .as Class I (seismic) structures. The spent f water. yy{ pit has a stainless steel liner to ensure against loss of The new and spent fuel storage ' racks are designed so that it is impossible to insert assemblies in other than the prescribed locations. The. fuel is.

stored vertically in a array with the center-to-center distance between assemblies sufficient to assure k <0.95 even if unborated water were

-used to fill the pit.

In additioIf fuel in the storage pool shall have a U-235 loading of je39.0 grams of U-235 per axial centimeter of fuel assembly (average) .

The criticality. considerations as they relate to the dropping of a' spent fuel cask (i.e., heavy load) drop onto the racks has been evaluated. The maximum K has been calculated to be 0.949 at a water /UO rati f a 2.0 withaboIbkconcentrationof.1800 ppm. 2 B. Spent Fuel Storage Structure The spent fuel storage pool is enclosed witg y reinforced concrete building having 12-to 18-inch thick walls and roof. The pool and pool enclosure are Class I (seismic) structures that afford protection against loss of

= integrity from postulated tornado missiles. The storage compartments and the fuel transfer canal are connected by fuel transfer slots that can be

, closed off with pneumatically sealed gates. The bottoms of the slots are above the tops of the active fuel in the fuel assemblies -which will be stored vertically in specially constructed racks.

i The spent fuel-pool has a reinforced concrete bottom slab nearly 6 feet H thick and has been designed to minimize loss of water due to a dropped cask i

accident. In addition, the spent fuel cask will have an impact limiter attached or a crash pad will be in place in the pool which will have the' capability to absorb energy of impact due to a cask drop. This will result in no structural damage taking place to the pool which would res* ult in significant leakage from the pool. Piping to the pool is arranged so that

[ failure of any pipe cannot drain the pool below the tops of the stored fuel i- assemblies.

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i TS.S.6-2 REV C.- Fuel Handling .

The fuel handling. system provides the means of transporting and handling-fuel from the time it reaches the plant,in an unieradiated condition until it leaves af ter post-irradiation cooling. The system consists of the refueling cavity, the fuel transfer system, the spent fuel storage pit, and the spent fuel cask transfer system.

Major components of the fuel handling system are the manipulation crane, the spent fuel' pool bridge, the auxiliary building crane, the fuel transfer system,' the spent fuel storage racks, the spent fuel cask, and the rod cluster control changing fixture. The reactor vessel stud tensioner, the reactor vessel head lif ting device, and the reactor internals lifting device are used for preparing the reactor for refueling and for assembling the reactor after refueling.

Upon arrival in the storage pit, spent fuel will be removed from' the transfer system and placed, one assembly at a time, in storage' racks using a long-handle manual tool suspended from the spent fuel pit bridge crane.

Af ter sufficient decay, the fuel will be loaded into shipping casks for removal from the site. The casks will be handled by the auxiliary buildin'g crane.

The load drop consequences of a spent fuel cask for Prairie Island have been evaluated. It is not possible, due.to physical constraints, for a cask _ to be _ dropped into the large pool (pool no. 2). A load path has been defined which provides for safe movement of the cask. Travel interlocks and mechanical stops prevent cask movement outside of this path. The only safety-related equipment that can be impacted directly during a cask drop along this path is the fuel stored in the small pool (pool no. 1). The consequences of this drop have been evaluated and found to meet the NRC Staff criteria contained in NUREG-0612 if at least 50 days have elapsed since reactor shutdown for fission gas release considerations and the pool water contains at least 1800 ppa boron for criticality considerations. A cask impact limiter or crash pad prevents significant structural damage to the pool floor.

The spent fuel cask will be lowered 66 feet from the auxiliary building to the railroad car for offsite transportat' ion. Specification 3.8 will limit this loading operation so that if the cask drops 66 feet, there will not be a-significant release of fission products from the fuel in the cask.

D. Spent Fuel Storage Capacity The spent fuel storage facility is a two-compartment pool that, if completely filled with fuel storage racks, provides up to 1582 storage locations. The southeast corner of the small pool (pool No.1) also serves as the cask lay down area. During times when the cask is being used, four racks are removed from the small pool. With the four storage racks in the southeast corner of pool I removed, a total of 1386 storage locations are provided. To allow insertion of a shipping cask, total storage is limited to 1386 assemblies, not including those assemblies which can be returned to the reactor.

Reference (1) FSAR, Section 9.

EXHIBIT C PRAIRIE ISLAND NUCLEAR GENERATING PLANT LICENSE AMENDMENT REQUEST - DATED DECEMEER 21, 19tt4-

" Licensing Report for Prairie Island .

Nuclear Generating Plant _ Units 1 and 2 Spent Fuel Cask Drop Evaluation" Quadrex Report No. QUAD-1-83-017 Revision 2 dated 10/4/84

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